Cecil the lion backlash: Where is dentist Walter Palmer?

The Minnesota dentist has gone underground in the onslaught of criticism after he killed a prized African lion named Cecil.

It probably shouldn't come as a surprise; an angry horde of Cecil supporters is calling for his head to be mounted on a wall.

Meanwhile, the U.S. Fish and Wildlife Service is investigating the circumstances surrounding the lion's killing.

"At this point in time, however, multiple efforts to contact Dr. Walter Palmer have been unsuccessful. We ask that Dr. Palmer or his representative contact us immediately," said Edward Grace, the service's deputy chief of law enforcement.

CNN knocked on the door of his Minneapolis home, but no one answered.<